June 1, 2010
A newly published study's results provide perhaps the strongest evidence to date that the drugs used to treat HIV also prevent its spread. In a trial involving heterosexual couples where one partner was HIV-infected and the other was not, AIDS drugs reduced the risk of viral transmission to the uninfected partner by 92 percent.
In seven African countries, the researchers recruited 3,381 serodiscordant heterosexual couples. During the study, 349 people initiated antiretroviral therapy (ART) at a median CD4 cell count of 198. The other infected participants received a placebo. An ethics committee closely monitored the trial, whose components included a safe-sex training course and routine health checkups. Every three months, the uninfected partners were tested for HIV.
At 24 months, 103 partners who had been HIV-free at baseline had been infected by their partner. Genetic testing was used to confirm whether an infection had originated with the patient's partner or with someone outside the trial. Only one of the 103 genetically linked infections was transmitted by a partner on ART.
The scientists noted that ART may lower -- but does not eliminate -- the risk of transmission, so safe-sex counseling must remain a part of prevention efforts for serodiscordant couples.
"Low CD4 cell counts and high plasma HIV-1 concentrations might guide use of ART to achieve an HIV-1 prevention benefit," the authors concluded. "Provision of ART to HIV-1 infected patients could be an effective strategy to achieve population-level reductions in HIV-1 transmission."
The full report, "Heterosexual HIV-1 Transmission After Initiation of Antiretroviral Therapy: A Prospective Cohort Analysis," was published in The Lancet (2010; doi:10.1016/S0140-6736(10)60705-2).